Variety and Cultivation-practice Influences on the Growth Characteristics and Yield of Maize (Zea mays L.) under Drought Stress at Flowering
Abstract
In northeast Thailand, maize (Zea mays L.) is mainly grown under rainfed conditions. In this region, frequent dry spells are often the cause of periodic drought-stress that leads to decreased yields, especially during the critical growth stages. The objective of the study was to identify and assess variety and cultivation-practice effects on the growth and yield of maize under temporary drought stress induced during the flowering stage. Under controlled soil-moisture conditions, three varieties (Suwan5 - open-pollinating; Big717 and Big949 - single-cross hybrids) and five cultivation practices (conventional (CT); mungbean (Vigna radiata (L.) Wilzek) residue (Mn); spineless mimosa (Mimosa invisa) live mulch (Mi); manure (Ma); and plastic mulch (Pl) were studied for two cropping seasons.
There were significant variety differences, apparently independent of the cultivation practices. The two hybrid varieties produced significantly higher grain yields than the open-pollinating variety, i.e., Big717 > Big949 > Suwan5. The effects of cultivation practices were less prominent, with the exception of Suwan5, for which Mn, Mi, and Ma significantly reduced grain yields compared to CT and Pl. Big717 showed no significant differences between the treatments; Big949 showed significant treatment response only for the second crop, particularly for the Ma treatment. Overall, the highest average yields were produced by Pl; the lowest by Ma. However, there were no significant differences for the total aboveground biomass between cultivation practices, but between varieties -i.e., Suwan5 and the two hybrids. The two hybrids had clearly higher harvest indexes (HI) than the open pollinating variety. For Suwan5 and Big949 HI was consistently lowest with the Ma treatment.Th e general trend of the tasseling-silking interval (TSI) was Big949 > Suwan5 > Big717. For Big717, TSI was not affected by any cultivation practices. For the other two varieties, Ma showed longest TSI. Suwan5 grew more vigorously than the other varieties at the early vegetative stage. Within the varieties, the tallest plants were observed with Ma.
The effects of cultivation practices on the grain yield were less prominent than the variety effects; in some cases the practices, particularly Ma, even had a negative effect on the yield. Therefore, variety selection is still a potential management tool that can effectively control the effects of drought stress on the plants. It is however highly recommended that further studies should investigate plant responses for drought-stress periods during other growth stages and with different degrees of drought stress. On-farm trials under uncontrolled drought-stress conditions should be also carried out.
There were significant variety differences, apparently independent of the cultivation practices. The two hybrid varieties produced significantly higher grain yields than the open-pollinating variety, i.e., Big717 > Big949 > Suwan5. The effects of cultivation practices were less prominent, with the exception of Suwan5, for which Mn, Mi, and Ma significantly reduced grain yields compared to CT and Pl. Big717 showed no significant differences between the treatments; Big949 showed significant treatment response only for the second crop, particularly for the Ma treatment. Overall, the highest average yields were produced by Pl; the lowest by Ma. However, there were no significant differences for the total aboveground biomass between cultivation practices, but between varieties -i.e., Suwan5 and the two hybrids. The two hybrids had clearly higher harvest indexes (HI) than the open pollinating variety. For Suwan5 and Big949 HI was consistently lowest with the Ma treatment.Th e general trend of the tasseling-silking interval (TSI) was Big949 > Suwan5 > Big717. For Big717, TSI was not affected by any cultivation practices. For the other two varieties, Ma showed longest TSI. Suwan5 grew more vigorously than the other varieties at the early vegetative stage. Within the varieties, the tallest plants were observed with Ma.
The effects of cultivation practices on the grain yield were less prominent than the variety effects; in some cases the practices, particularly Ma, even had a negative effect on the yield. Therefore, variety selection is still a potential management tool that can effectively control the effects of drought stress on the plants. It is however highly recommended that further studies should investigate plant responses for drought-stress periods during other growth stages and with different degrees of drought stress. On-farm trials under uncontrolled drought-stress conditions should be also carried out.
Keywords
cultivation practice; drought stress; maize; Thailand; Zea mays L.
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